1. Technical Field
This invention relates generally to a fascia for a portable electronic device, and more specifically to a fascia assembly having a thin, flexible membrane that serves both as a depressible keypad and as a display.
2. Background Art
Portable electronic devices, such as mobile telephones, portable music players, and portable gaming devices, are becoming more and more commonplace. While once a rare luxury, it is now not uncommon to see a person with two or three electronic devices operating simultaneously. For example, a businessperson commuting to work may have a mobile telephone for receiving calls, a portable music player for listening to music, and a wireless messaging device for sending e-mail and browsing the Internet. Advances in engineering and design have made these devices increasingly affordable.
In addition to reducing prices, advances in technology have also reduced the size of these devices. While a mobile telephone in the early 1980s came in a bag and was about the size of a shoe, today's mobile telephones easily slip into a shirt pocket. The devices are becoming more stylish as well. By way of example, the RAZR mobile telephone, manufactured by Motorola, Inc., has won critical acclaim for its sleek, ultra thin design. Consumers sometimes give as much weight to the aesthetic appearance of a device when making a purchase as they do to the device's feature set. As such, the trend for designers is to create smaller devices without compromising aesthetic appeal.
There are problems, however, in attempting to design new, smaller, more fashionable devices. One problem involves tooling limitations in the manufacture of exterior housing components of these devices. The most common way to manufacture durable housing components for rechargeable battery packs is by way of injection molding. In the injection molding process, molten plastic is injected into the cavity of a metal mold. The plastic flows throughout the cavity, thereby filling it. When the plastic cools, the mold is opened and the plastic part is removed.
The problem with this process is that there is a fundamental limit to the minimum thickness per unit area of the walls of any part. This is due to the flow of the molten plastic. If the cavity in the mold includes passages that are too thin, the plastic will not flow properly through these thin regions. Improper plastic flow leads to parts with walls that break easily or have holes in them. The net result is a battery housing with walls that fall apart too easily.
A second problem involves the user interface. Injection molded parts are generally manufactured from rigid materials such as polycarbonate and ABS resins. To incorporate a user interface, such as a keypad for example, the designer must add holes for keys and buttons. By adding these holes, the plastic remaining between the holes must be increased in thickness to provide the overall rigidity. This increased bulk can compromise the aesthetic appearance.
There is thus a need for an improved electronic device housing that offers a thinner, yet still reliable, housing component.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.